Here is my stack trace which occured
According to my knowledge this error is occuring when our application tries to connect with the data base and while executing the first function which has some validation with the database, the above error is coming.

Also some have suggested that this error is because of log4j API bug.IF it is so please give me a solution to rectify that.

for temporary purpose when we have restarted the application server it is not coming and again after some days say 15 to 20
this is again happening.Please provide me a solution.

javax.ejb.EJBException: java.lang.NullPointerException; nested exception is:
java.lang.NullPointerException; nested exception is: oracle.oc4j.rmi.OracleRemoteException: java.lang.NullPointerException; nested exception is:
java.lang.NullPointerException oracle.oc4j.rmi.OracleRemoteException: java.lang.NullPointerException at com.evermind.server.ejb.EJBUtils.getUserException(EJBUtils.java:346)
at com.evermind.server.ejb.interceptor.system.AbstractTxInterceptor.convertAndHandleMethodException(AbstractTxInterceptor.java:69)
at com.evermind.server.ejb.interceptor.system.TxRequiredInterceptor.invoke(TxRequiredInterceptor.java:52)
at com.evermind.server.ejb.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:119)
at com.evermind.server.ejb.interceptor.system.DMSInterceptor.invoke(DMSInterceptor.java:52)
at com.evermind.server.ejb.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:119)
at com.evermind.server.ejb.InvocationContextPool.invoke(InvocationContextPool.java:55)
at com.evermind.server.ejb.StatefulSessionEJBObject.OC4J_invokeMethod(StatefulSessionEJBObject.java:844)
at LoginSessionEJB_RemoteProxy_2ekhpah.checkPassword(Unknown Source)
at sun.reflect.GeneratedMethodAccessor236.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.evermind.server.rmi.RmiMethodCall.run(RmiMethodCall.java:53)
at com.evermind.util.ReleasableResourcePooledExecutor$MyWorker.run(ReleasableResourcePooledExecutor.java:303)
at java.lang.Thread.run(Thread.java:595)

Nested exception is:
java.lang.NullPointerException at org.apache.log4j.Category.removeAllAppenders(Category.java:888) at bsnl.pms.common.sessionbeans.LoginSessionEJBBean.checkPassword(LoginSessionEJBBean.java:468)
at sun.reflect.GeneratedMethodAccessor237.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.evermind.server.ejb.interceptor.joinpoint.EJBJoinPointImpl.invoke(EJBJoinPointImpl.java:35)
at com.evermind.server.ejb.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:119)
at com.evermind.server.ejb.interceptor.system.SetContextActionInterceptor.invoke(SetContextActionInterceptor.java:44)
at com.evermind.server.ejb.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:119)
at com.evermind.server.ejb.interceptor.system.DMSInterceptor.invoke(DMSInterceptor.java:52)
at com.evermind.server.ejb.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:119)
at com.evermind.server.ejb.interceptor.system.TxRequiredInterceptor.invoke(TxRequiredInterceptor.java:50)
at com.evermind.server.ejb.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:119)
at com.evermind.server.ejb.interceptor.system.DMSInterceptor.invoke(DMSInterceptor.java:52)
at com.evermind.server.ejb.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:119)
at com.evermind.server.ejb.InvocationContextPool.invoke(InvocationContextPool.java:55)
at com.evermind.server.ejb.StatefulSessionEJBObject.OC4J_invokeMethod(StatefulSessionEJBObject.java:844)
at LoginSessionEJB_RemoteProxy_2ekhpah.checkPassword(Unknown Source)
at sun.reflect.GeneratedMethodAccessor236.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.evermind.server.rmi.RmiMethodCall.run(RmiMethodCall.java:53)
at com.evermind.util.ReleasableResourcePooledExecutor$MyWorker.run(ReleasableResourcePooledExecutor.java:303)
at java.lang.Thread.run(Thread.java:595)
javax.ejb.EJBException: java.lang.NullPointerException; nested exception is:
java.lang.NullPointerException; nested exception is: oracle.oc4j.rmi.OracleRemoteException: java.lang.NullPointerException; nested exception is:
java.lang.NullPointerException at com.evermind.server.rmi.RMICall.EXCEPTION_ORIGINATES_FROM_THE_REMOTE_SERVER(RMICall.java:109)
at com.evermind.server.rmi.RMICall.throwRecordedException(RMICall.java:125)
at com.evermind.server.rmi.RMIClientConnection.obtainRemoteMethodResponse(RMIClientConnection.java:517)
at com.evermind.server.rmi.RMIClientConnection.invokeMethod(RMIClientConnection.java:461)
at com.evermind.server.rmi.RemoteInvocationHandler.invoke(RemoteInvocationHandler.java:63)
at com.evermind.server.rmi.RecoverableRemoteInvocationHandler.invoke(RecoverableRemoteInvocationHandler.java:28)
at com.evermind.server.ejb.StatefulSessionRemoteInvocationHandler.invoke(StatefulSessionRemoteInvocationHandler.java:31)
at __Proxy1.checkPassword(Unknown Source)
at bsnl.pms.common.actions.LoginAction.login(LoginAction.java:96)
at sun.reflect.GeneratedMethodAccessor254.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:280)
at org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:216)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:484)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:274)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:763)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
at com.evermind.server.http.ServletRequestDispatcher.invoke(ServletRequestDispatcher.java:711)
at com.evermind.server.http.ServletRequestDispatcher.forwardInternal(ServletRequestDispatcher.java:368)
at com.evermind.server.http.HttpRequestHandler.doProcessRequest(HttpRequestHandler.java:866)
at com.evermind.server.http.HttpRequestHandler.processRequest(HttpRequestHandler.java:448)
at com.evermind.server.http.AJPRequestHandler.run(AJPRequestHandler.java:302)
at com.evermind.server.http.AJPRequestHandler.run(AJPRequestHandler.java:190)
at oracle.oc4j.network.ServerSocketReadHandler$SafeRunnable.run(ServerSocketReadHandler.java:260)
at com.evermind.util.ReleasableResourcePooledExecutor$MyWorker.run(ReleasableResourcePooledExecutor.java:303)
at java.lang.Thread.run(Thread.java:595)
Caused by: oracle.oc4j.rmi.OracleRemoteException: java.lang.NullPointerException; nested exception is:
java.lang.NullPointerException at com.evermind.server.ejb.EJBUtils.getUserException(EJBUtils.java:346)
at com.evermind.server.ejb.interceptor.system.AbstractTxInterceptor.convertAndHandleMethodException(AbstractTxInterceptor.java:69)
at com.evermind.server.ejb.interceptor.system.TxRequiredInterceptor.invoke(TxRequiredInterceptor.java:52)
at com.evermind.server.ejb.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:119)
at com.evermind.server.ejb.interceptor.system.DMSInterceptor.invoke(DMSInterceptor.java:52)
at com.evermind.server.ejb.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:119)
at com.evermind.server.ejb.InvocationContextPool.invoke(InvocationContextPool.java:55)
at com.evermind.server.ejb.StatefulSessionEJBObject.OC4J_invokeMethod(StatefulSessionEJBObject.java:844)
at LoginSessionEJB_RemoteProxy_2ekhpah.checkPassword(Unknown Source)
at sun.reflect.GeneratedMethodAccessor236.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.evermind.server.rmi.RmiMethodCall.run(RmiMethodCall.java:53)
... 2 more
Caused by: java.lang.NullPointerException at org.apache.log4j.Category.removeAllAppenders(Category.java:888)
at bsnl.pms.common.sessionbeans.LoginSessionEJBBean.checkPassword(LoginSessionEJBBean.java:468)
at sun.reflect.GeneratedMethodAccessor237.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.evermind.server.ejb.interceptor.joinpoint.EJBJoinPointImpl.invoke(EJBJoinPointImpl.java:35)
at com.evermind.server.ejb.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:119)
at com.evermind.server.ejb.interceptor.system.SetContextActionInterceptor.invoke(SetContextActionInterceptor.java:44)
at com.evermind.server.ejb.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:119)
at com.evermind.server.ejb.interceptor.system.DMSInterceptor.invoke(DMSInterceptor.java:52)
at com.evermind.server.ejb.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:119)
at com.evermind.server.ejb.interceptor.system.TxRequiredInterceptor.invoke(TxRequiredInterceptor.java:50)
... 12 more